Apparatus for controlling the temperature of a fluid



Dec. 10, 1935. c u woo 1- AL 2,023,627

APPARATUS FOR CONTROLLING THE TEMPERATURE OF A FLUID Filed Dec. 10, 19512 Sheets-Sheet l 10, 1935- c. M. UNDERWOOD El AL 2,023,627

I ABPATKATUS FOR CONTROLLING THE TEMPERATURE OF A FLUID Filed Dec. 10,1951 2 Sheets-Sheet 2 Wye/Wars 6! M Underwaad Patented Dec. 10, 1935UNITED STATES PATENT OFFICE APPARATUS FOR CONTROLLING THE TEIWPERATUREOF A FLUID Application December 10, 1931, Serial No. 580,112 10 claims.(on. 236-4) This invention relates to an apparatus for controlling thetemperature of a fluid and more particularly to an apparatus forcontrolling the amount of heat supplied to a steam superheater.

5 An object of the invention is to provide an effective and efiicientapparatus for controlling the temperature of a fluid.

In the process of tinning wire strands using a steam wiper for removingexcess tin from the 10 strands, superheated steam is frequently suppliedto a large number of wipers and the amount of steam required varies withthe number of wipers in operation at any particular time. Thus forinstance the amount of steam required may 10 vary quite abruptly whenone of the tinning machines is stopped due, to a broken strand or thelike, or when the number of machines in operation is increased ordecreased.

As long as the amount of steam flowing through 20 a superheater isconstant, the amount of heat supplied to the heating coils may besubstantially constant, but when the rate of flow of the steamincreases, the amount of heat supplied must be increased to maintain therequired temperature of the superheated steam and when rate of flow ofthe steam decreases the amount of heat supplied must be decreased toprevent burning out the coils of the superheater.

In accordance with one embodiment of the invention, the amount of heatsupplied to heat the steam is varied both in accordance with the rate offlow of the steam and in accordance with the temperature of the steam.

A complete understanding of the invention may 35 be had by reference tothe following description taken in conjunction with the accompanyindrawings, in which Fig. 1 is a schematic view of an apparatus embodyingthe invention, and 40 Fig. 2 is a schematic view of a modified form ofthe invention.

I Referring now particularly to Fig. 1 a steam superheater 6 is shownhaving an inlet conduit 1 which delivers steam to the superheater froma' 45 conventional boiler (not shown).

An outlet conduit 8 from the heater leads to a steam wiping device 9 ofa tinning machine, such as is more fully disclosed in the copendingapplication of C. M. Underwood, Serial No. 331,362, filed Januarycommonly used in steam superheaters. In the inlet conduit of thesuperheater an apertured diaphragm i3 is located and on each side of thediaphragm is a tube M. These tubes lead to a mercury contact device Ihaving a longitudinal 5 passage I6 therein at the ends of which areupwardly extending arms I? and I8. The passage i6 is filled with aconducting liquid, such as mercury, which extends upwardly into arms i?and iii a short distance. The device I5 is pivoted 10 at 99 and thelower ends of tubes M are provided with a turn encircling the pivot 59and then extend into the upper ends of arms I1 and it. The purpose ofthe turns in the tubes is to increase the flexibility of the tubes. seenthat when no steam is flowing in the conduit l, the static pressure ofthe steam will be equal on both sides of diaphragm l3 and, therefore,the level of the mercury in arms I7 and 98 will be equal. However, whenthere is a flow of steam through conduit 1, the pressure on theright-hand tube It will decrease, causing the mercury in arm 88 to riseand the mercury in arm H to fall.

The ends of arms ii and I8 are closed by taps and a common conductor 21leads from the electromagnets to one line of a source of three phasealternating current. The body of the device I5 is made of conductingmaterial and is connected to another line of the three phase source ofalternating current through a conductor 28. Assuming that no steam isflowing in conduit 1, the apparatus will be substantially in theposition shown in Fig. 1. If steam is now caused to .flow in conduit Iby opening a valve 29 leading to the steam wiper of the tinning machine,,the'mercury will rise in arm l8 and engage the contact in the upper endof this arm, closing the circuit through magnet 26, thereby actuating anarm 3| of a reversing switch .32 to energize a three phase motor 33.This motor has an elongated threaded shaft 34 which carries aninternally threaded memb'er 35. The member 35 ,has a link 36 pivotallyconnected thereto which is in turn pivotally connected to a downwardlyextending arm 31 of contact device l5. The direction of rotation ofmotor 33 when electromagnet 26 is energized is such as to move themember 35 to the right and this causes the contact device to tilt aboutits pivot point l9 and disengage the mercury in arm I 8 from the It willbe 15 contact, thereby causing the electromagnet 26 to be de-energized,whereupon the arm 3| of reversing switch 32 will be returned to neutralposition by means of a spring 38. This de-energizes the motor and causesit to stop. While the motor was rotating and moving the member 35 to theright, it also actuated a valve 4| through a link 42 for controlling theamount of fuel supplied to the superheater through a pipe 43. The

distance which member is moved to the right, and, therefore, the amountthatv valve 4| is opened, depends upon the height to which the mercurylevel is raised in arm l8 as a result of the flow of steam in conduit 1.

If now' the rate of flow of steam in conduit I decreases, as, forinstance, when the valve 29 is partially closed, the mercury will fallin arm l8 and rise in arm l1, causing the mercury to engage the contactin the upper end of arm H to energize electromagnet 25. The energizationof electromagnet 25 moves the arm 3| of reversing switch 32 to its upperposition, thereby energizing motor 33 in such a direction as to causeitto rotate'in the opposite direction from that previously described,moving the member 35 to the left. This movement continues until themercury in arm I! disengages the contact in that arm to de-energizeelectromagnet 25 allowing a spring 48 to move arm 3| of the reversingswitch to neutral position to de-energize the motor, at which time thevalve 4| will have been closed to such a position as to supply theproper amount of fuel to the superheater for the rate of steam flowingtherethrough. The amount of movement of valve 4| relative to the amountof tilting of the contact device may be varied by adjusting the link 36vertically in the slot in arm 31.

.-It is important in a steam wiper of. a thinning machine that theheater steam be held at a rather uniform temperature in order to insurea uniform coating on the tinned strand. Another reason for regulatingthe amount of heat supplied to the pipes of the superheater is thatunless the heat is taken away from the pipes at the same rate at whichit is supplied, the pipes will very rapidly become overheated and burnout. It is impor-' tant, therefore, that the fuel supplied to the-super-heater be reduced immediately as soon as the rate of flow ofsteam through the superheater decreases. I

It has been found that the temperature of the steam at the output end ofthe superheater should also be taken into consideration in determiningthe amount of heat supplied to the superheater. For this purpose athermocouple 44 is placed in the outlet conduit 8 and is connected to agalvanometer 45. This galvanometer is provided with two contacts 46 and41, one of which is connected to an electromagnet 48, while the other isconnected to an electromagnet 49. A common conductor 5| of theelectromagnets is connected through a source of electrical energy 52 tothe pointer of the galvanometer. Whenthe temperature of the steam inconduit 8 is low, the pointer will engage contact 46 and energizeelectromagnet 48. The valve 4|, previously referred to, is a the'flow offuel to the superheater. When the pointer of the galvanometer is in aneutral position, piston 53 will be in its neutral reciprocableposition; and when the pointer moves into engagement with contact 41,electromagnet 48 will be energized to further close the opening throughvalve 4|. Thus it will be seen that the action of the valve, due to theflow of steam through the superheater, is modified to a certain extentby the temperature of the steam.

In the embodiment of the invention shown in Fig. 2, a superheater 6 isprovided with an inlet conduit 1, and an outlet conduit 8 leads to asteam wiping device 9 of a tinning machine. The conduit I is providedwith a diaphragm l3 on each side of which is a flexible tube l4 lead--ing to a contact device 6|. This contact device 'has two arms 62 and 63which are connected by a passage 64. The top of the contact device ispreferably made of insulating material and each arm has three contactstherein. The arm 62 has contacts 65, 66, 61 and the arm 63 has contacts68, 68 and II sealed through the insulating top of the device.

the device.

Cooperating with the contact device is a galvanometer I3 which iscontrolled by a thermocouple 14 in the outlet conduit 80f thesuperheater. having two radially spaced contacts, the upper one of whichis connected to an electromagnet 16 and the lower one is connected to anelectromagnet TI. The galvanometer also has two sets of plates spaced atdifferent radial distances from the pivot point of the pointer, one setcomprising plates 65 66 and 61 which are electrically connected tocontacts 65, 66 and 61, respectively; and the other set of platescomprising plates 68 69 and I I which are electrically connected tocontacts 68, 63 and II of contact device 6|. The electromagnets I6 and11 are connected to one line of a three phase source of alternatingcurrent by a conductor 18 and the body of the contact device 6|, whichis made of conducting material, is connected by a conductor 19 toanother terminal of. the three phase source of alternating current.-

It will be seen that only two of the six contacts of the contact devicewill be effective at one time. If the pointer 15 of the galvanometer isin its left-hand position, as a result of a low temperature of the steamin conduit 8, contacts 65 and 68 will be connected to theelectromagnets. When the pointer 15 is vertical, indicating a mediumtemperature of the steam in conduit 8, the contacts 66 and '69 will beconnected to the vanometer is in the right-hand position engaging plate61 andlfl indicating high temperature of the steam in conduit 8, thecontacts 61 and 1| "will be connected to the electromagnets.-

The galvanometer has a pointer l5 The contacts in each arm aresuccessively spaced farther from the pivot point of I Now when there isno steam flowing through conduit 1, the static pressure of the steam oneach side of diaphragm l3 will be equal and the device will besubstantially in the position shown in Fig. 2. If now the valve 16 isopened, causing a flow of steam through conduit 1, the pressure"; I onthe right-hand pipe M will be reduced, caus.

ing the mercury to rise in arm 63 and fall in arm;

62. As soon as the mercury in arm 63 makes en-'- 83 is provided with athreaded shaft 84 carrying. an internally threaded member 85. At theupper end of this member a link 88 is pivotally connected to contactdevice 6| and a second link 8'! is connected to the lower side of member85 for operating a valve 88. The direction of rotation of motor 88,'whenelectromagnet i5 is energized, is such as to move the member 85 to theright, as viewed in Fig. 2, tilting the device 6! so as to break theconnection between the mercury and contact 68, while at the same timethe valve 88 is opened to supply more fuel to the superheater.

If the rate of flow of steam in conduit E. decreases, the mercury in arm88 will drop and the mercury in arm 62 will rise, engaging contact 65which causes the electromagnet H to be energized to reverse thedirection of rotation of the motor until the connection b'etween themercury and contact 85 is broken, while at the same time partiallyclosing valve 88. If the temperature of the steam in conduit 8increases, the pointer will move into such a position as to contact withplates 86 and 88 At this time contacts 65 and 68 will become inoperativeand contacts 66 and 89 will become operative. With these connectionswhen the mercury in arm 83 rises, it will be seen that a connectionbetween mercury and contact 88 will be broken sooner by the tilting ofcontact 6| than the connection between the mercury and contact 68. As aconsequence thereof, valve 88 will not be opened as far when the pointerof the galvanometer is in engagement with plates 66 and 69 as it wouldbe if the pointer were in engagement with plates 65 'and 68 When thepointer is in engagement with plates 61 and H the connection between themercury and contact ll will be broken upon a still smaller movement ofmember 85. The amount of movement of the\ valve 88 relative to thetilting of the contact device may be varied by adjusting the link 86vertically in the slot in the downwardly extending arm of the contactdevice.

In order to move the valve toward its closed position, the proceduretakes place in just a reverse order. If the pointer 151s in engagementwith plates 61 and il the valve 88 will be closed farther to break thecontact between the mercury in arm 82 and contact 65, than itwould be ifthe arm were in engagement with contacts 65 and 68 because in that casethe valve would have to be 7 closed only far enough to break theconnection between themercury in arm 62 and contact t7. When the mercuryis not engaged with any of the contacts, the arm 8! of reversing switch82 is held in neutral position by springs 89 and ill.

The apparatus described controls the temperature of the superheatedsteam, both in accordance with the temperature of the steam and the rateof flow thereof. It has been found that the temperature of thesuperheated steam cannot be controlled by a temperature responsivecontrol alone. For instance, the thermo-couple temperature controldescribed in connection with the apparatus is capable of controlling thetemperature only of the steam in the output conduit 8. However, sincethe heat is being supplied to the coils in the superheater, thetemperature of the steam in ,the superheater when the steam in thesuperheater is not moving at all or moving slowly may be much higherthan at the point where the thermocouple is located, so that it would bepossible to completely burn out the coils in the superheater withoutshutting oil? the fuel supply by means of the temperature control. Whilethe control of the temperature of the superheated steam is bestcontrolled by the-rate of flow of the steam through the superheatenthisin itself is not completely satisfactory because the moisture of thesteam fed to the superheater through 5 the conduit i may vary, and alsothe: richness or mixture of the fuel may vary, making it necessary tosupply difierent amounts of fuel with a constant rate of flow of steamthrough the superheater. I 10 The apparatus described above combinesboth of these control features, which are correlated in such a mannerthat the action of one modifies the action of another.

It will be understood that the nature and embodiments of the inventionherein described and illustrated are merely convenient and useful formsof the invention and that many changes and modifications may be madetherein without departing from the spirit and scope of the invention.

What is claimed is:

1. In an apparatus for controlling the temperature of a fluid, atiltable liquid contact device, means for rendering said deviceresponsive to fluid pressure due to the flow of the fluid, an electricalcircuit associated with said contact device, a source of motive power,'means for controllin said motive power in accordance with the combinedeffect of the tilted position of and fluid 7 pressure in said device,and means actuated by said source of motive power for controlling theheat supplied to the fluid.

2. In an apparatus for controlling the temperature of a fluid, atiltable liquid contact device, means for rendering said deviceresponsive to fluid pressure due to the flow of the fluid, an electricalcircuit associated with said contact device, a source of motive power,means for controlling said motive power in accordance with the combinedeffect of the tilted position of and fluid pressure in said device,means actuated by said source of motive power for controlling the heatsupplied to the fluid, and means responsive to the temperature of thefluid for modifying the effect of the tiltable liquid contact device.

3. In an apparatus for controlling the temperature of a fluid, means forheating the fluid, a mercury contact device having two upwardlyextending arms, means actuated in accordance with the differentialpressure of the fluid for controlling the level of mercury in said arms,an electrical circuit having contacts extending into said arms, saidcircuit being associated with a source of power, means for closing thecircuit through said source of power when the mercury in one arm risesto a predetermined level, means for opening said circuit when the sourceof power has moved a predetermined distance, and means actuated by saidsource of power for controlling the amount of heat supplied to thefluid.

4. In an apparatus for controlling the temperature of a fluid, means forheating the fluid, a mercury contact device having two upwardlyextending arms, means actuated in accordance with the differentialpressure of the fluid for controlling the level of mercury in said arms,an electrical circuit having contacts extending into said arms, saidcircuit being associated with a source of power, means for closing thecircuit through said source of power when the mercury in one arm risesto a predetermined level, means for opening said circuit when the sourceof power has moved a predetermined distance, means actuated by saidsource of power for controlling the amount of heat supplied to thefluid, and means responsive to the ing the level of mercury in saidarms, an electric motor, means for energizing the motor when the mercuryin one of said arms reaches a predetermined level, means for causing themotor to tilt said device to de-energize the motor, means controlled bythe temperature of the fluid for rendering various of said contactseffective, and

means actuated by the motor for controlling the amount of heat suppliedto the fluid.

6. In an apparatus for controlling a fluid, a movable contact device,means for applying a difierential fluid pressure thereto in response tothe rate of flow of said fluid and rendering said device responsive tosaid differential fluid pressure, an electrical circuit associated withsaid contact device, a source of motive power for positioning saiddevice, means for controlling said motive power in accordance with thecombined efiect of the said differential fluid pressure in the contactdevice and position of said device, and means actuated by said source ofpower for controlling a condition of the fluid.

'7. In an apparatus forcontrolling a fluid, a contact device operabledirectly in response to the flow of the fluid, a second contact deviceoperable in response to the temperature of the fluid, and an electricalcircuit including means operable to combine the eflects of said contactdevices to control the fluid; I

8. In an apparatus for controlling a condition a fluid, a tiltableliquid contact device, means for rendering said device responsive tofluid pres- 5 sure due to the flow of the fluid, an electrical circuitassociated with said contact device, a source of motive power, means forcontrolling said source in accordance with the combined effect of thetilted position of and fluid pressure in said device, and means actuatedby said source 01' motive power for controlling said condition.

9. In an apparatus for controlling a fluid, a movable contact device,means for rendering said device responsive to a diflerential fluidpressure in response to the rate of flow of said fluid, a source ofmotive power for positioning said movable contact device, and means forcontrolling said motive power in accordance with the combined eiTect orthe differential fluid pressure in response to the rate of flow of saidfluid in and position of said contact device to control a condition ofsaid fluid.

10. In an apparatus for controlling a fluid, a movable contact device,means for rendering said device responsive to a differential fluidpressure in response to the rate of flow of said fluid, a source ofmotive power for positioning said movable contact device, means forcontrolling said motive power in accordance with the combined effect ofthe differential fluid pressure in and position of said contact device,means actuated by said source of power for controlling a condition ofthe fluid, and means responsive to the temperature of the fluid formodifying said control.

CARL M. UNDERWOOD. EMERSON PUGH.

